The invention relates to a combined ampule-oneway injection syringe comprising a syringe body destined for accommodating the injection liquid, and a needle-carrying connection piece.
Injection syringes of this kind have been offered separately as a storage container containing medicament and as a pertaining antiseptically packed connection piece carrying the needle. The connection piece with the needle is slipped on the syringe cone by the physician prior to the application. This manipulation bears the risk of bacterial contamination, thus defeating the object, which would be obtainable with oneway injection syringes in which the connection between the syringe body and the connection piece having the injection needle is undetachable, of assuring that, after filling of the syringe body with the medicament, sterile conditions are safeguarded until the application of the medicament.
Ampule-oneway injection syringes which include injection needles that are undetachably fastened thereto and whose syringe bodies contain the medicament and are closed by a movable piston, are well known. With these, the injection needle is glued into the syringe cone by a glue having a polyester base. These ampule-oneway injection syringes, however, have the disadvantage that they are difficult to produce because the inner wall of the syringe body has to be treated with a lubricant, advantageously with silicone, which is evaporated onto the wall at approximately 300.degree. C. The polyester glue, however, cannot withstand these high temperatures without changing its color or being destroyed. Also when inversely operating, i.e. introducing the lubricant first and gluing on the needle afterwards, unsolvable difficulties will frequently occur, since a silicone-treated surface evidently will not accept a glue. The known ampule-oneway injection syringes of this kind have the further disadvantage that it is necessary to keep an extensive stock since every needle dimension (length and diameter) and every syringe body has to be produced as a production unit; it therefore is not possible to assemble a desired, separately produced needle of a particular dimension with a desired, separately produced syringe body prior to filling the body with the medicament.
Moreover, ampule-oneway injection syringes have also been known to have a double needle undetachably fastened to one end and a glass body containing the medicament, which glass body is insertable into the syringe body. The glass body comprises a rubber closure with a welt at the side of the needle and is closed by a displaceable piston at the other side. Injection syringes of this kind are accordingly expensive.